Evaluation of different heat extraction strategies for shallow vertical ground-source heat pump systems

Retkowski, Waldemar; Ziefle, Gesa; Thöming, Jorg

doi:10.1016/j.apenergy.2015.03.004

Cited by 28 publications

(8 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The main notion behind Equation ( 7) is that it allows the physical domain which consists of concentric layers of grout and soil to be discretized into finite volumes. After control volume discretization is performed, Equations (8)(9)(10)(11)(12)(13)…”

Section: Numerical 2d Finite-volume Modelmentioning

confidence: 99%

See 1 more Smart Citation

Numerical heat transfer comparison study of hybrid and non-hybrid ground source heat pump systems

2016

View full text Add to dashboard Cite

Ground Source Heat Pump (GSHP) systems, if improperly designed may lead to overheating or overcooling of the ground. Good designs ensure properly balanced energy storage through adequately sizing ground-loops. Hybrid systems combine conventional Heating, Ventilating, and Air Conditioning (HVAC) with GSHPs in order to significantly reduce the high installation costs of GSHPs. The hybrid systems are designed in such a way that GSHPs provide the base building energy demands while the conventional HVAC is used only during the peak hours. In general, all buildings can be divided into two main categories: cooling dominant and heating dominant. If a building is cooling dominant, ground temperature increases with time and in heating dominant cases it decreases. A severe ground temperature increase/decrease is referred to as 'ground fouling' because it can render the GSHP inoperable, as temperature differences are required to maintain controlled heat flow. This paper compares long-term operation of hybrid and nonhybrid GSHP systems in order to investigate the effectiveness of hybridization at alleviating 'ground fouling'. A homespun 2D finite-volume model is proposed to study heat transfer in ground coupled heat pump systems and is verified against an analytical solution as well as experimental data. Through simulation of different building types, it is demonstrated that hybridization has potential to reduce 'ground fouling' but only in limited cases for which a large portion of the energy demands is being met by the conventional HVAC.

show abstract

Section: Numerical 2d Finite-volume Modelmentioning

confidence: 99%

“…Retkowski et al evaluated the best heat extraction strategies for GSHPs [12] and proposed a new bi-criteria mixed-integer nonlinear program (MINLP) for an optimal peak load design [13].…”

Section: Introductionmentioning

confidence: 99%

Numerical heat transfer comparison study of hybrid and non-hybrid ground source heat pump systems

2016

View full text Add to dashboard Cite

show abstract

“…The changes in underground temperatures are calculated through analytic-solution-based tools [16,17] or by using numerical simulation software [18,19]. The analytical calculation is effective in saving computational time, especially for multiple BHEs [20]. Previous studies have shown the effectiveness of the simulation approach for the evaluation of parameter sensitivity and for optimization of system performance in targeted buildings [21,22].…”

Section: Introductionmentioning

confidence: 99%

Nationwide Determination of Required Total Lengths of Multiple Borehole Heat Exchangers under Variable Climate and Geology in Japan

Sakata

Katsura

Nagano

2021

IJGI

View full text Add to dashboard Cite

This study determined the required lengths of borehole heat exchangers (BHEs) in ground-source heat pump systems for heating/cooling a building (with 300 m2 of floor area) across Japan’s four main islands through a simulation approach. Hourly thermal loads were estimated in 10 km gridded cells based on the outside temperature and humidity. Three-dimensional estimates of ground thermal conductivity from our previous study at the depths of the BHEs were used. A 5-year system operation was simulated in a total of 4059 cells with 81 combinations of individual lengths and total numbers of BHEs to determine the shortest total length required to achieve sustainable use and targeted performance. The optimal combination of individual length and total number varied regionally due to climate conditions and locally among adjacent cells due to geological conditions. The total required lengths ranged widely from 78 to 1782 m. However, the lengths were less than 400 m in 85% of the cells. Additionally, cost-effectiveness in 69% of the cells was shown by reducing the total lengths to half or less of those in the practical method. The reduction could potentially increase the feasibility of heat pump system use in Japan. The total lengths were dependent on the heating/cooling loads approximately as secondary-polynomial functions, but the relations with the ground thermal conductivity were not clear.

show abstract

“…A first order analysis is presented, it being clear that -as with many other energy technologies (e.g. Spitler, 2005;Murphy et al 2015;Alahäivälä et al 2015;Liu et al 2015;Retkowski et al 2015;Safdarnejad et al 2015;Walraven et al 2015;Yun et al 2015) -great potential exists for optimizing the proposed general form of the solution. 10…”

mentioning

confidence: 99%

“…There is thus scope for 10 exploring the possibilities for integrating these systems with other infrastructure, for example using heat pumps to match the required input and output temperatures (cf. Hesaraki et al 2015;Liu et al 2015;Retkowski et al 2015), as well as investigating the ability of this technology to handle heat storage from intermittent sources such as those noted above. 15 Some key implications of the preceding analysis will now be addressed.…”

mentioning

confidence: 99%

Repurposing of disused shale gas wells for subsurface heat storage: preliminary analysis concerning UK issues

Westaway

2016

QJEGH

View full text Add to dashboard Cite

Westaway, R. (2016) Repurposing of disused shale gas wells for subsurface heat storage: preliminary analysis concerning UK issues. Quarterly Journal of Engineering Geology and Hydrogeology, 49, pp. 213-227. (doi:10.1144/qjegh2016-016) This is the author's final accepted version.There may be differences between this version and the published version. Abstract: Development of many wells is envisaged in the UK in coming decades to exploit the abundant shale gas resource as fuel and petrochemical feedstock. Forward planning is therefore warranted regarding reuse of the resulting subsurface infrastructure after gas production has 10 ceased. It is shown that this infrastructure might be repurposed for Borehole Thermal Energy Storage (BTES). Preliminary calculations, assuming an idealized cycle of summer heat storage and winter heat extraction, indeed demonstrate annual storage of ~6 TJ or ~2 GWh of energy per BTES well. Summed over the anticipated well inventory, a significant proportion of the UK's future heat demand might thus be supplied. This form of BTES technology has particular 15 relevance to the UK, where the shale resource is located in relatively densely populated areas; it is especially significant for Scotland, where the resource coincides with a particularly high proportion of the population and heat demand.

show abstract

Evaluation of different heat extraction strategies for shallow vertical ground-source heat pump systems

Cited by 28 publications

References 36 publications

Numerical heat transfer comparison study of hybrid and non-hybrid ground source heat pump systems

Numerical heat transfer comparison study of hybrid and non-hybrid ground source heat pump systems

Nationwide Determination of Required Total Lengths of Multiple Borehole Heat Exchangers under Variable Climate and Geology in Japan

Repurposing of disused shale gas wells for subsurface heat storage: preliminary analysis concerning UK issues

Contact Info

Product

Resources

About